Method for manufacturing continuous sheets of bread dough

ABSTRACT

Methods and apparatuses are disclosed for producing a continuous belt-like sheet of bread dough. The apparatus consists of a dough hopper, vertical conveyors mounted on the facing side walls of the hopper, a dough outlet provided at the bottom of the hopper, and a pair of discharging rolls constituting part of the dough outlet, facing each other, and which are rotated so as to downwardly pass the bread dough passing therebetween. The width of the outlet and the peripherial speed of the discharging rolls are controllable so that a high-quality sheet of bread dough is continuously produced, while the gel structure of the dough is maintained uninjured.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method and apparatus for shaping elasticmaterials such as bread dough, and, more particularly, to a method andapparatus for producing a continuous sheet of bread dough.

2. Prior Art

In the prior art method for producing bread a large mass of dough,prepared by kneading flour, water, etc., by a mixer, is metered and thendivided into small pieces of dough in the first process. Each piece isof the same weight as that of an end product. Sometimes the end productis very small. There are many inconveniences in this process in thatwhen very small pieces of dough are to be formed at the beginning, thebread-making process is often complicated, errors in the weight of theproducts are large, the efficiency of the process is hindered, and therange within which the size of the products can be changed is limited.

Producing bread by first forming a continuous belt-shaped dough sheetand then dividing it into pieces of dough that are the size of pieces ofbread has also been developed as prior art. However, due to thecharacteristics of the bread dough itself, namely, the gel structure ofgluten and the high elasticity resultant from such structure, it hasbeen difficult to produce a continuous belt of bread dough with sectionsof a uniform weight. Hence, such a belt of bread dough is conventionallyproduced by repeatedly passing bread dough between a pair of rollers andthus the elastic bread dough is forcibly moved and the gel structure isdestroyed.

That is, this prior art method of producing bread dough is a way ofplastic molding, in which rollers exert a repetitive application offorce on the bread dough. This method is not suited for producingtraditional high-quality bread comparable to hand-made bread. Thus, asmentioned above, in the method of the prior art, it is more often thannot that after mixing the ingredients the bread dough is first dividedinto small round pieces. The dough pieces are then aged for a long timeto restore the original gel structure of the protein. This effect is tobe induced by an oxidizing agent that had been added in advance to thedough. The dough is then shaped and baked.

U.S. Pat. No. 4,629,110 discloses an apparatus for stretching dough inwhich a plurality of conveyors, each driven at a different speed, areserially disposed. It has a roller mechanism comprising a plurality ofrollers that are freely rotatable about their axes, that constitute astraight path, and which are spaced apart from and located over theconveyors. Although in these prior art apparatuses the dough is smoothlystretched, the roller mechanism has a heavy and complex mechanism, sothat it requires high production, maintenance, and repair costs.Therefore, an apparatus for stretching dough that is simple, functionssteadily, and that has low production costs, has been desired.

Accordingly, one of the objects of this invention is to provide a methodand apparatus for producing a continuous belt of bread dough withoutdestroying the gel structure of the bread dough by allowing it to freelyflow within the limit of its inherent elasticity.

Another object of this invention is to provide a method and apparatusfor steadily and continuously supplying a belt-like bread dough sheet tocontinuously produce dough products.

Still another object of this invention is to provide a method andapparatus for producing a sheet of dough adaptable for the efficientproduction of dough products.

SUMMARY OF THE INVENTION

In accordance with these and other objects, this invention provides animproved method and apparatus for producing a sheet of continuousbelt-like bread dough. In one aspect of this invention the methodconsists of the steps of conveying bread dough downward by verticalconveyors that are mounted on two sides of a dough hopper that consistsof an inlet, a hopper body, and an outlet, and controlling thecross-sectional area of the outlet such that the amount of the breaddough discharged from the outlet corresponds to the supply of breaddough passing downward through the hopper body.

In accordance with another aspect of this invention an apparatus isprovided that consists of a dough hopper, vertical conveyors mounted onthe facing sides of the hopper, a dough outlet provided at the bottom ofthe hopper and consisting of a space between a pair of discharging rollsfacing each other, and rotated so as to pass downwardly the bread doughpassing therebetween, wherein the cross-sectional area of the outlet andthe peripheral speed of the discharging rolls are controllable.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic sectional front view of an embodiment of anapparatus of this invention for manufacturing a sheet of belt-like breaddough.

FIG. 2 is a schematic partial cross section of the apparatus of FIG. 1.It explains the functions of each component of the apparatus.

FIG. 3 is a schematic block diagram to explain the functional system ofthe apparatus.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In FIG. 1, a hopper 101 receives, stocks, and transfers bread dough 1,which has been kneaded by a mixer (not shown). The hopper consists of aninlet 2 and a box-like body 18 downwardly extending from the inlet, anda pair of discharging rolls 3 defining an outlet 19 therebetween. Theinlet 2 has a wide top opening to receive dough and a narrowed bottomconnected to the box-like hopper body 18. The body 18 is rectangular incross section. It is confined by a front wall, a rear wall, and two sidewalls. Each of the two side walls is constituted by a vertical conveyor4. Each vertical conveyor consists of a conveyor belt wound around tworolls, one of which is driven by a motor 8 (FIG. 3). The other roll isfreely rotatable. The inner flight of each conveyor is designed to movedownward, as shown by arrows g, at the same speed.

The speed of the vertical conveyors 4 is adjustable by adjusting thedriving mechanism. The speed is selected so that the dough within thehopper body 18 descends at substantially the same speed as that of thevertical conveyors.

At the bottom of the body 18 a pair of discharging rolls 3 are disposedso that they face each other. They rotate in the same direction wherethey face each other. The gap between the rolls constitutes an outlet 19for the dough. The distance between the discharging rolls 3 can beadjusted by moving one or both of the rolls horizontally, as will beexplained later in connection with FIG. 3.

Beneath the outlet 19 is provided an inclined conveyor 6 consisting of abelt wound around rolls 20, 21, and 22. The roll 21 is positionedimmediately beneath the outlet 19 and forms a flight for the belttogether with the roll 22 so that the belt forms an inclined passage forthe dough pouring from the outlet 19. The roll 20 is driven by a motor(not shown), and the other two rolls are freely rotatable.

A transfer conveyor 7 is provided underneath the inclined conveyor 6.The transfer conveyor 7 consists of a conveyor belt wound about tworolls 23 and 24 and has a lengthy upper flight. The roll 23 is driven bya motor 10 (FIG. 3) and the other roll 24 is freely rotatable. Variousshaping apparatuses, including a divider 15 for dividing the dough sheet5 and a wind-up means 16, are disposed along the downstream part of thetransfer conveyor 7. The divider 15 is a vertical cutter with an edge atits bottom, arranged to make vertical reciprocal movements to cut thedough sheet 5 on the transfer conveyor 7. The wind-up means 16 consistsof a chain-belt form metal sheet suspended from a horizontal barcrossing the transfer conveyor 7 above it.

A speed sensor V is provided underneath one of the rolls 3 to measurethe speed f of the dough sheet passing through the gap of thedischarging rolls 3. A weight sensor G is mounted to a frame (not shown)under the top flight of the transfer conveyor 7 at a point downstream ofthe inclined conveyor 6. It continuously measures the weight g of thebelt-like dough sheet 5 passing over it, so that the unit of productionper unit time can always be indicated, based on the measurements ofspeed d.

FIG. 2 schematically shows the positional and functional relationshipsamong the components that constitute the apparatus. When thecross-sectional area of the space formed between the facing verticalconveyors 4 is assumed to be D, the cross-sectional area of the spaceformed between facing discharging rolls 3 is assumed to be F, thedifference between the sectional areas D and F is assumed to be S, thespeed of the vertical conveyors 4 is assumed to be a, the peripheralspeed of the discharging rolls 3 is assumed to be b, and the flow speedof the dough sheet, which is measured just after it has passed throughthe discharging rolls 3 is assumed to be f, the function of theapparatus is designed so as to realize the following equation:

    D a/F b=k

wherein k is a constant.

The above is based on the observation that when an instantaneous forcethat is exerted on the bread dough that is being fed through the hopperbody always corresponds to an instantaneous force that is exerted on thebread dough that is being discharged through the discharging rolls, thegel structure of the dough is not injured, and that this condition canbe substantially fulfilled when the instantaneous volume of the doughdescending through the hopper body is proportional to that of the doughgoing out through the discharging rolls, as shown by the above equation,provided that the proportion between b and f is within a certain range,which range depends on the nature of the dough being fed.

The cause of this limitation in the range of the proportion between band f is the need to avoid the generation of an eddy that is generatedby the resistance of dough around the lower part of the verticalconveyors against the driving force from the descending verticalconveyors, caused by the difference between D and F, which causes aturbulent flow.

In the apparatus of this invention the difference S between D and F isintentionally provided as a function that is needed to steadilydischarge the accurately sheeted bread dough. It has been experimentallyproven that even if F is smaller than D, the gel structure of thedischarged dough remains uninjured in so far as the above-mentionedequation is fulfilled and it equals b or f is within a range ofproportion to b that avoids a turbulent flow. This range varies widelydepending on the consistency of the dough, the ratio of speed a to speedb, and the ratio of area F to area D etc.

In the apparatus of this invention dough flows freely while the inherentstrength of the gel is kept unchanged. Dough sheeting is achieved byallowing the elastic behaviour of the gel of the dough to move freely soas to obtain products of a stable quality that are steadily dischargedthrough the apparatus, without damaging the characteristics of the doughmaterials, such as viscoelasticity.

Since what destroys the gel structure is a shearing stress, and thestress is caused by excessive differences in the speed of the flow amongparts of the dough and eddies that are generated inside the dough whenit is flowing, the method and apparatus of this invention aims atreducing such a shearing stress.

In the method of this invention, a pair of vertical conveyors 4 mountedon the two sides of a hopper body causes dough 1 to move downward sothat no difference in speed is generated between the downward movementof the surfaces of dough 1 facing the inner surface of the hopper body18 and that of the central part of the dough 1. The gap between the pairof rolls 3 provided at the bottom of the hopper is adjusted depending onthe gel strength of the dough, so that the generation of the shearingstress at around the outlet is controlled, and when the gap between therolls are adjusted, the peripheral speed of the rolls 3 issimultaneously adjusted so that the following equation is automaticallyrealized:

    D a/F b=k

Thus, due to this mechanism of this invention, the generation of an eddyaround the outlet of the discharging rolls is avoided so that a constantquantity of the sheeted bread dough can be continuously and steadilydischarged.

In FIGS. 1 and 2, the conveying speed of the inclined conveyor 6 isindicated by c, and that of the transfer conveyor 7, by d. They aresubstantially the same as the speed of f of the dough coming out of therollers 3.

In FIG. 3, the rotational speeds of all motors for driving the conveyorsand discharging rolls are controlled by a computer 25. The lower roll ofone of the vertical conveyors is driven by a motor 8. A chain belt iswound around a sprocket attached to the shaft of the motor and the shaftof the roll to convey the driving force to the roll. The lower roll ofthe other conveyor is also similarly connected by another chain belt andsprocket assembly so that the latter is driven via the roll of the firstconveyor. The discharging rolls 3 are driven by the motor 9. The rollsare operatively connected to the motor 9 by a horizontal shaft extendingfrom the motor. The shaft is provided with worms meshing with a wormwheel mounted to an end of each discharging roll 3. The transferconveyor 7 is connected to a motor 10 by means of a chain and sprocketassembly. Inverters 28, 29, and 30 for adjusting each of the speeds ofthe motors are connected between the motors 8, 9, and 10 and thecomputer 25. The computer 25 always determines the optimum instantaneousspeeds for each of the motors based on information on the peripheralspeed of the rolls 3, b. This information is derived from the speed ofthe motor 9 for driving the roll 3 given through feedback linesconnecting the motor 9 and the computer 25 via the inverter 29,discharging dough speed f derived from sensor V, weight of the doughsheet 5 derived from sensor G, and on the gap of the outlet 19, which isobtained by a counter 31 provided near the base for the motor 9. Theinformation on the gap is obtained by a gap-setting handle 11, which isattached to an end of a bar that is threaded through an end platemounted on each discharging roll 3. When the handle 11 is operated thegap is set such that a clockwise movement of the handle causes the rollsto move apart and a counterclockwise movement causes the rolls to movecloser. The drawing shows a manually operated handle, but it can beoperated automatically based on computer calculation. A gap indicator12, discharging roll peripheral speed meter 13, and discharging doughspeed meter 14, show relevant values for visual observation.

The operation of the apparatus of this invention will now be explainedby reference to FIGS. 1 and 3. The bread dough is fed into the hopperinlet 2 and then to the box-like body. When the vertical conveyors 4start moving downward as shown by arrows a and the rolls 3 startrotating as shown by arrows b, a belt-like bread dough sheet 5 comes outof the outlet 19. The discharged belt-like bread dough is transferred byan inclined conveyor 6 to a transfer conveyor 7. The dough sheet is thencut by the divider 15, rolled up by the wind-up means 16, and fed to asubsequent station.

When the dough leaves the rolls 3, the speed of the dough flow f and theperipheral speed b of the discharging rolls 3 are compared by thecomputer 25. When the ratio between them is not within the standardrange, the handle 11 is operated to adjust the gap so as to attain aratio within the standard range. If the handle 11 is operated, both thesectional area F of the outlet and the peripheral speed b of the rollsare automatically adjusted by the computer 25 so as to realize theequation D a/F b=k.

The adjustment is carried out such that when the handle 11 is operatedthe information from the computer 31 is fed into the computer, and thenthe computer causes an inverter 29 to drive. It controls the motor 9according to the gap information to adjust the speed of the dischargingrolls 3.

The weight sensor G mounted on the transfer conveyor 7 detects theweight of the produced dough sheet 5. The weight information is fed intothe computer, via an output indicator 26, to simultaneously driveinverters 28, 29, and 30 so that the rotational speeds of the motors fordriving the vertical conveyors 4, the discharging rolls 3, and thetransfer conveyors 10, respectively, are adjusted by using predeterminedconversion ratios, so as to automatically maintain a constant productionamount of the dough sheet throughout the operation of the apparatus. Theproduction amount of the dough sheet is indicated by an output indicator26.

THE EFFECTS OF THE INVENTION

As is explained above, by providing vertical feeding conveyors anddischarging rolls so that the amount of the supply of bread doughsubstantially coincides with the discharge of the bread dough, and bycontrolling the gap between the discharging rolls so that thedischarging speed of the dough corresponds to the peripheral speed ofthe discharging rolls, the method and apparatus of this invention cancontinuously produce a stable high-quality belt-like sheet of breaddough, while maintaining the gel structure of the dough uninjured.

I claim:
 1. A method for producing a continuous belt-like sheet of breaddough, comprising the steps ofconveying bread dough downward by verticalconveyors that are mounted on two sides of a dough hopper consisting ofan inlet, a hopper body, and an outlet, and controlling the crosssection of the outlet such that the amount of the bread dough dischargedfrom the outlet corresponds to the amount of bread dough supplied thatpasses downward through the hopper body.
 2. A method for producing acontinuous belt-like sheet of bread dough, comprising the stepsofconveying bread dough downwardly through a hopper consisting of aninlet, a hopper body having two facing sides each of which is provided avertical conveyor, and an outlet, the outlet being formed by a spacebetween a pair of discharging rolls, controlling the cross-sectionalarea of the outlet such that the amount of the bread dough dischargedfrom the outlet proportionally corresponds to the amount of the breaddough passing downward through the hopper body, and controlling thespeed of the discharging rolls so as to establish a constantrelationship between the peripheral speed of the discharging rolls andthe speed of the bread dough that is passing through the outlet.